userfaultfd: shmem: __do_fault requires VM_FAULT_NOPAGE
[ Upstream commit 6bbc4a4144
]
__do_fault assumes vmf->page has been initialized and is valid if
VM_FAULT_NOPAGE is not returned by vma->vm_ops->fault(vma, vmf).
handle_userfault() in turn should return VM_FAULT_NOPAGE if it doesn't
return VM_FAULT_SIGBUS or VM_FAULT_RETRY (the other two possibilities).
This VM_FAULT_NOPAGE case is only invoked when signal are pending and it
didn't matter for anonymous memory before. It only started to matter
since shmem was introduced. hugetlbfs also takes a different path and
doesn't exercise __do_fault.
Link: http://lkml.kernel.org/r/20170228154201.GH5816@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
9bcd15bdfb
commit
275314e90c
|
@ -419,7 +419,7 @@ int handle_userfault(struct fault_env *fe, unsigned long reason)
|
|||
* in such case.
|
||||
*/
|
||||
down_read(&mm->mmap_sem);
|
||||
ret = 0;
|
||||
ret = VM_FAULT_NOPAGE;
|
||||
}
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in New Issue